Prior to the present invention, as is generally quite well known in the railway car coupling art, passenger transit type railway cars have generally been equipped to enable an automatic coupling of the electric train lines disposed on such railway cars to be accomplished. The electric coupling equipment, used to accomplish the task of automatically coupling these electric train lines, has normally been disposed either on the top portion, or on the bottom portion, or on the side portions of the mechanical type coupler mechanism.
The electrical contacts which are required for connecting such electric train lines together are, as a general rule, disposed within an electric coupling box member. Such electric coupling box is disposed on the mechanical type coupling mechanism in a position to, first, allow movement in a forward direction upon completion of the mechanical coupling operation of the adjacently disposed ends of the railway cars and, secondly, to allow movement in a reverse direction when a mechanical uncoupling operation of such railway cars is required.
In this known fashion, the necessary electrical connection is accomplished with an adjacently disposed car, thereby enabling the completion of the necessary electrical circuits. On the other hand, the electric coupler box member is designed to be retracted in an axially opposed backward direction upon the receipt therein of an uncoupling command input signal and prior to allowing the mechanical uncoupling of such adjacently disposed ends of the railway cars to be accomplished.
The physical movements which such electric coupler box member is required to make have been accomplished, prior to the development of the present invention, by the suspension of such electric coupler box member on a guide means. Such guide means is normally attached, in a first method known to applicants, to the mechanical type coupling mechanism. This prior art attachment method makes use of guide wheels which are disposed on the electric coupler box member.
In a second method, also, known by the applicants to be used prior to the development of the present invention for achieving the required physical movements of such electric coupler box member, such electric coupler box member was designed in a manner which enabled it to slide in a longitudinal direction on a machined surface which is equipped with side guides.
However, both of the above described prior art type methods will inherently require extremely close design tolerances to be incorporated therein. As would be expected, such extremely close design tolerances have added significantly to the manufacturing cost for such electric coupling box members. Additionally, these extremely close design tolerances have been found to still allow unacceptably excessive frictional wear to occur to a significant number of certain critical railway car components. Such critical components at least include the electric contacts located in the electric coupler box members, wheels, machined surfaces and side guides.